1. Technical Field
The invention relates to vacuum cleaners. Particularly, the invention relates to a height adjustment mechanism for vacuum cleaners. Even more particularly, the invention relates to a height adjustment mechanism which includes a height adjustment cam formed with a ribbed camming surface for reducing the amount of force required to adjust the vacuum cleaner nozzle height.
2. Background Information
Because different types of carpets have different pile heights, conventional upright vacuum cleaners include variable height nozzles. A foot of these conventional uprights include some type of nozzle height adjustment mechanism which allows a user to adjust the height of the nozzle relative to a floor surface being cleaned.
Typically, these height adjustment mechanisms include a wheel carriage pivotally mounted to the foot of the upright vacuum cleaner. A height adjustment cam having a camming surface engages the wheel carriage and pivots the wheel carriage to raise or lower the height of the nozzle opening relative to the floor. The height adjustment cam is engaged by a cam actuator, such as a slide member, which is accessible from the outer surface of the foot. Such a height adjustment mechanism is shown and described in U.S. Pat. No. 5,134,750, assigned to a common assignee.
Although these prior art height adjustment mechanisms are adequate for the purpose for which they are intended, it is desirable to reduce the amount of force necessary to move the cam actuator to raise and lower the nozzle height. Such a reduction in force may be accomplished by reducing the surface-to-surface contact between the camming surface of the cam actuator and the wheel carriage. This reduced contact would reduce the amount of frictional resistance between the two members, thus requiring less force to operate the cam actuator.
Therefore, the need exists for a height adjustment mechanism which provides an easily operated cam actuator for raising and lowering the nozzle height relative to the floor surface.